NO. 1483. riiOCOPTTD MOLLU.SK.S—BARTSCH. 147 



but somewhat .sinuous. The entire free portion is encircled b}' strong;- 

 Hnes of o-rowth, which as usual become weaker and more crowded 

 behind the peristome. Aperture small, o])lique, broadl}^ oval, the 

 pari(»tal wall representing the short diameter of the oval. Peristome 

 very thin, moderately expanded and somewhat reflexed. Internal 

 piUar large, about one-lifth the diameter of the shell, straight and 

 narrowed to less than half the diameter in the last whorl, thin, marked 

 only by whitish lines of growth. There are three specimens of this 

 species in the collection of the U. S. National Museum, Cat. No. 

 13J:69i», collected by E. W. Nelson at Encarnacion, Hidalgo, Mexico. 

 The perfect specimen, the type, has 17 whorls and measures: Length 

 15.2 mm.; diameter of thirteenth whorl, 4.2 mm.; diameter of penul- 

 timate whorl, 4 mm. 



HOLOSPIRA (HAPLOCION) TANTALUS, new species. 

 Plate III, fig. 6. 



Shell small, pupoid, yellowish white. Nuclear whorls one and one- 

 half, well rounded, very minutely granulose. Terminal cone gently 

 tapering, having the sloping whorls somewhat overhanging; whorls of 

 the cylindrical portion of the spire moderately rounded. The entire 

 post-nuclear spire is marked by feeble, obliquely backward slanting 

 riblets, which are better developed and a little more distantl}- spaced 

 on the terminal cone and the last two volutions than on the middle of 

 the spire. There are about 52 of these riblets upon the thiixl whorl, 

 al)out loo upon the seventh and about 85 upon the penultimate turn. 

 Sutures well marked. Peripher^^ of the last whorl slighth^ angulated. 

 Base short, well rounded, deeply rimate, marked b}^ the little riblets. 

 Last whorl scarcely free, the peristome adnate to the outer wall of the 

 preceding volution. Aperture moderately large, subcircular, with a 

 decidedly thickened white peristome, which is broadly expanded and 

 very slightly reflected. Internal column slender, straight, increasing 

 gradually in diameter from the last whorl to the early whorls of the 

 terminal cone, smooth, marked onl}^ by whitish lines of growth. 



There are two specimens of this species in the collection of the U. S. 

 National Museum Cat. No. 29303. They were collected l)y Dr. Edward 

 Palmer somewhere in Arizona or New Mexico. They have been cited 

 in several places as Ilolosjjira jnlshri// Dii\\, but their internal struc- 

 ture, as well as other features, mark them as quite distinct. The two 

 s^iecimens measure: 



